In order to satisfy the demand of peak spectrum efficiency, support for eight antennas at a base station side is added during formulation of a Long Term Evolution Advanced (LTE-A) standard for a new generation of wireless cellular mobile communication system.
A codebook for eight-antenna is designed by using a codebook for two-antenna and a codebook for four-antenna to produce a Kronecker product, and use the codebook for four-antenna and the codebook for two-antenna to produce a Kronecker product, so as to generate a full rank codebook CB8(8) for eight-antenna, which is specifically shown in Formula (1):
                                                        CB              8                              (                8                )                                      ⊆                          M              ⁢                                                          ⁢              C              ⁢                                                          ⁢                              B                8                                  (                  8                  )                                                              =                                    {                                                                    W                                          (                      2                      )                                                        ⊗                                      W                                          (                      4                      )                                                                      ❘                                                      W                                          (                      n                      )                                                        ∈                                      CB                    n                                          (                      n                      )                                                                                  }                        ⋃                          {                                                                    W                                          (                      4                      )                                                        ⊗                                      W                                          (                      2                      )                                                                      ❘                                                      W                                          (                      n                      )                                                        ∈                                      CB                    n                                          (                      n                      )                                                                                  }                                      ⁢                                  ⁢                                  ⁢                                                            where                ⁢                                                                  ⁢                                  w                                      (                    2                    )                                                              ∈                              CB                2                                  (                  2                  )                                                      =                          {                                                                    1                                          2                                                        ⁡                                      [                                                                                            1                                                                          1                                                                                                                      1                                                                                                      -                            1                                                                                                                ]                                                  ,                                                      1                                          2                                                        ⁡                                      [                                                                                            1                                                                          1                                                                                                                      j                                                                                                      -                            j                                                                                                                ]                                                              }                                ,                                    (        1        )            n is equal to 2 or 4, W(2) is a codeword in the codebook for two-antenna, W(4) is a codeword in the codebook for four-antenna, CB2(2) is a full rank codebook for two-antenna, and CB4(4) is a full rank codebook for four-antenna. The codeword for eight-antenna does not adapt to characteristics of a dual-polarization channel, and cannot be effectively applied to a dual-polarization antenna.